1. Field of the Invention
The present invention relates to a communication device and a method used in a wireless communication system, and more particularly, to a communication device and a method of handling a radio resource control connection.
2. Description of the Prior Art
A long-term evolution (LTE) system provides high data rate, low latency, packet optimization, and improved system capacity and coverage. In the LTE system, a radio access network known as an evolved universal terrestrial radio access network (E-UTRAN) includes at least one evolved Node-B (eNB) for communicating with at least one user equipment (UE), and for communicating with a core network including a mobility management entity (MME), a serving gateway, etc., for Non-Access Stratum (NAS) control.
A LTE-advanced (LTE-A) system, as its name implies, is an evolution of the LTE system. The LTE-A system targets faster switching between power states, improves performance at the coverage edge of an eNB, increases peak data rate and throughput, and includes advanced techniques, such as carrier aggregation (CA), coordinated multipoint (CoMP) transmissions/reception, uplink (UL) multiple-input multiple-output (UL-MIMO), licensed-assisted access (LAA) using LTE, etc. For a UE and an eNB to communicate with each other in the LTE-A system, the UE and the eNB must support standards developed for the LTE-A system, such as the 3rd Generation Partnership Project (3GPP) Rel-10 standard or later versions.
The UE may transmit a message for resuming a radio resource control (RRC) connection to a network when the UE needs to transmit data, after the RRC connection is suspended by the network. However, the network may reject the resumption of the RRC connection performed by the UE. According to the prior art, it is unknown whether resources corresponding to the RRC connection are valid or not, when the network rejects the resumption of the RRC connection. It may cause the consumption of resources. On the other hand, the resumption of the RRC connection performed by the UE may be failed. According to the prior art, it is unknown how to handle the failure of the resumption.
Thus, how to handle the RRC connection is a problem to be solved.